Impact of Multiple Ecological Stressors on a Sub-Arctic Ecosystem: No Interaction Between Extreme Winter Warming Events, Nitrogen Addition and Grazing
Climate change is one of many ongoing human-induced environmental changes, but few studies consider interactive effects between multiple anthropogenic disturbances. In coastal sub-arctic heathland, we quantified the impact of a factorial design simulating extreme winter warming (WW) events (7 days a...
Published in: | Frontiers in Plant Science |
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Online Access: | http://hdl.handle.net/11250/2576027 https://doi.org/10.3389/fpls.2018.01787 |
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ftninstnf:oai:brage.nina.no:11250/2576027 2023-05-15T14:58:07+02:00 Impact of Multiple Ecological Stressors on a Sub-Arctic Ecosystem: No Interaction Between Extreme Winter Warming Events, Nitrogen Addition and Grazing Bokhorst, Stef Berg, atty P. Edvinsen, Guri K. Ellers, Jacintha Heitman, Amber Jaakola, Laura Mæhre, Hanne K. Phoenix, Gareth K. Tømmervik, Hans Bjerke, Jarle W. 2018 application/pdf http://hdl.handle.net/11250/2576027 https://doi.org/10.3389/fpls.2018.01787 eng eng urn:issn:1664-462X http://hdl.handle.net/11250/2576027 https://doi.org/10.3389/fpls.2018.01787 Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no Copyright © 2018 Bokhorst, Berg, Edvinsen, Ellers, Heitman, Jaakola, Mæhre, Phoenix, Tømmervik and Bjerke. CC-BY Frontiers in Plant Science cryptogam CO2 fluxes fatty acids frost geometrid moth herbivory multiple stress snow VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480 Peer reviewed 2018 ftninstnf https://doi.org/10.3389/fpls.2018.01787 2021-12-23T07:16:56Z Climate change is one of many ongoing human-induced environmental changes, but few studies consider interactive effects between multiple anthropogenic disturbances. In coastal sub-arctic heathland, we quantified the impact of a factorial design simulating extreme winter warming (WW) events (7 days at 6–7 C) combined with episodic summer nitrogen (CN) depositions (5 kg N ha�����1) on plant winter physiology, plant community composition and ecosystem CO2 fluxes of an Empetrum nigrum dominated heathland during 3 consecutive years in northern Norway. We expected that the CN would exacerbate any stress effects caused by the WW treatment. During WW events, ecosystem respiration doubled, leaf respiration declined (�����58%), efficiency of Photosystem II (Fv/Fm) increased (between 26 and 88%), while cell membrane fatty acids showed strong compositional changes as a result of the warming and freezing. In particular, longer fatty acid chains increased as a result ofWWevents, and eicosadienoic acid (C20:2) was lower when plants were exposed to the combination of WW and CN. A larval outbreak of geometrid moths (Epirrita autumnata and Operophtera brumata) following the first WW led to a near-complete leaf defoliation of the dominant dwarf shrubs E. nigrum (�����87%) and Vaccinium myrtillus (�����81%) across all experimental plots. Leaf emergence timing, plant biomass or composition, NDVI and growing season ecosystem CO2 fluxes were unresponsive to the WW and CN treatments. The limited plant community response reflected the relative mild winter freezing temperatures (�����6.6 C to �����11.8 C) recorded after the WW events, and that the grazing pressure probably overshadowed any potential treatment effects. The grazing pressure and WW both induce damage to the evergreen shrubs and their combination should thereforebe even stronger. In addition, CN could have exacerbated the impact of both extreme events, but the ecosystem responses did not support this. Therefore, our results indicate that these sub-arctic Empetrum-dominated ecosystems are highly resilient and that their responses may be limited to the event with the strongest impact. Text Arctic Climate change Empetrum nigrum Northern Norway Norwegian Institute for Nature Research: Brage NINA Arctic Norway Frontiers in Plant Science 9 |
institution |
Open Polar |
collection |
Norwegian Institute for Nature Research: Brage NINA |
op_collection_id |
ftninstnf |
language |
English |
topic |
cryptogam CO2 fluxes fatty acids frost geometrid moth herbivory multiple stress snow VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480 |
spellingShingle |
cryptogam CO2 fluxes fatty acids frost geometrid moth herbivory multiple stress snow VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480 Bokhorst, Stef Berg, atty P. Edvinsen, Guri K. Ellers, Jacintha Heitman, Amber Jaakola, Laura Mæhre, Hanne K. Phoenix, Gareth K. Tømmervik, Hans Bjerke, Jarle W. Impact of Multiple Ecological Stressors on a Sub-Arctic Ecosystem: No Interaction Between Extreme Winter Warming Events, Nitrogen Addition and Grazing |
topic_facet |
cryptogam CO2 fluxes fatty acids frost geometrid moth herbivory multiple stress snow VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480 |
description |
Climate change is one of many ongoing human-induced environmental changes, but few studies consider interactive effects between multiple anthropogenic disturbances. In coastal sub-arctic heathland, we quantified the impact of a factorial design simulating extreme winter warming (WW) events (7 days at 6–7 C) combined with episodic summer nitrogen (CN) depositions (5 kg N ha�����1) on plant winter physiology, plant community composition and ecosystem CO2 fluxes of an Empetrum nigrum dominated heathland during 3 consecutive years in northern Norway. We expected that the CN would exacerbate any stress effects caused by the WW treatment. During WW events, ecosystem respiration doubled, leaf respiration declined (�����58%), efficiency of Photosystem II (Fv/Fm) increased (between 26 and 88%), while cell membrane fatty acids showed strong compositional changes as a result of the warming and freezing. In particular, longer fatty acid chains increased as a result ofWWevents, and eicosadienoic acid (C20:2) was lower when plants were exposed to the combination of WW and CN. A larval outbreak of geometrid moths (Epirrita autumnata and Operophtera brumata) following the first WW led to a near-complete leaf defoliation of the dominant dwarf shrubs E. nigrum (�����87%) and Vaccinium myrtillus (�����81%) across all experimental plots. Leaf emergence timing, plant biomass or composition, NDVI and growing season ecosystem CO2 fluxes were unresponsive to the WW and CN treatments. The limited plant community response reflected the relative mild winter freezing temperatures (�����6.6 C to �����11.8 C) recorded after the WW events, and that the grazing pressure probably overshadowed any potential treatment effects. The grazing pressure and WW both induce damage to the evergreen shrubs and their combination should thereforebe even stronger. In addition, CN could have exacerbated the impact of both extreme events, but the ecosystem responses did not support this. Therefore, our results indicate that these sub-arctic Empetrum-dominated ecosystems are highly resilient and that their responses may be limited to the event with the strongest impact. |
format |
Text |
author |
Bokhorst, Stef Berg, atty P. Edvinsen, Guri K. Ellers, Jacintha Heitman, Amber Jaakola, Laura Mæhre, Hanne K. Phoenix, Gareth K. Tømmervik, Hans Bjerke, Jarle W. |
author_facet |
Bokhorst, Stef Berg, atty P. Edvinsen, Guri K. Ellers, Jacintha Heitman, Amber Jaakola, Laura Mæhre, Hanne K. Phoenix, Gareth K. Tømmervik, Hans Bjerke, Jarle W. |
author_sort |
Bokhorst, Stef |
title |
Impact of Multiple Ecological Stressors on a Sub-Arctic Ecosystem: No Interaction Between Extreme Winter Warming Events, Nitrogen Addition and Grazing |
title_short |
Impact of Multiple Ecological Stressors on a Sub-Arctic Ecosystem: No Interaction Between Extreme Winter Warming Events, Nitrogen Addition and Grazing |
title_full |
Impact of Multiple Ecological Stressors on a Sub-Arctic Ecosystem: No Interaction Between Extreme Winter Warming Events, Nitrogen Addition and Grazing |
title_fullStr |
Impact of Multiple Ecological Stressors on a Sub-Arctic Ecosystem: No Interaction Between Extreme Winter Warming Events, Nitrogen Addition and Grazing |
title_full_unstemmed |
Impact of Multiple Ecological Stressors on a Sub-Arctic Ecosystem: No Interaction Between Extreme Winter Warming Events, Nitrogen Addition and Grazing |
title_sort |
impact of multiple ecological stressors on a sub-arctic ecosystem: no interaction between extreme winter warming events, nitrogen addition and grazing |
publishDate |
2018 |
url |
http://hdl.handle.net/11250/2576027 https://doi.org/10.3389/fpls.2018.01787 |
geographic |
Arctic Norway |
geographic_facet |
Arctic Norway |
genre |
Arctic Climate change Empetrum nigrum Northern Norway |
genre_facet |
Arctic Climate change Empetrum nigrum Northern Norway |
op_source |
Frontiers in Plant Science |
op_relation |
urn:issn:1664-462X http://hdl.handle.net/11250/2576027 https://doi.org/10.3389/fpls.2018.01787 |
op_rights |
Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no Copyright © 2018 Bokhorst, Berg, Edvinsen, Ellers, Heitman, Jaakola, Mæhre, Phoenix, Tømmervik and Bjerke. |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.3389/fpls.2018.01787 |
container_title |
Frontiers in Plant Science |
container_volume |
9 |
_version_ |
1766330206341038080 |